More than half (59 per cent) do not know what the pupil does and 42 per cent have no idea of the purpose of the retina.

The research, by online optical retailer Vision Direct, found two of the most common eye conditions were also a source of confusion.

Almost 1.8 million (4 per cent) believe hyperopia, far-sightedness, was a region in ancient Egypt while a similar number (4 per cent) thought presbyopia, short-sightedness, was a blockbuster sci-fi movie.

Well over 2 million adults (4 per cent) also wrongly claimed that epidexipteryx, a bird-like dinosaur, was an eye condition.

One in 20 (4 per cent) incorrectly believe that taraxacum - the Latin name for a dandelion - was a sight-affecting ailment.

Our lack of knowledge when it comes to eye health isn't helped by irregular eye tests.

Of the 2,000 people asked, one in seven (14 per cent) haven't had a check-up in the last five years despite NHS guidelines recommending an eye test at least every two years.

The survey, to mark World Glaucoma Week (11-18 March) also found that many are unable to name common eye conditions.

The condition, of which around 480,000 are living with, means the optic nerve, which connects the eye to the brain, has become damaged.

While there are no symptoms to begin with, it can develop over many years affecting peripheral vision first.

If left undiagnosed and untreated, it can lead to loss of vision.

Only 41 per cent could identify astigmatism as an eye-related condition.

While just a third (36 per cent) knew that macular degeneration affected sight.

Brendan O'Brien, of Vision Direct, said “It doesn't surprise us that many people are unable to name the most common eye conditions.

“However, in some cases, this lack of knowledge could be causing them to put off getting their eyes tested regularly.

“Getting your eyes checked is the only way to spot and manage these common conditions and getting to them earlier is vital.”

Temperatures in Britain have taken a sharp dip this week and officials have warned the elderly and those with health conditions take extra care.

Bone-chilling winds sweep in from the Russian Arctic and snowfall has been almost constant in many parts of the country.

While the wintery weather conditions have sparked excitement among some people, the cold blast could trigger or worsen symptoms of certain illnesses and health conditions.

The NHS lists the illnesses and ailments common during cold weather, including influenza.

Flu can be a major killer of vulnerable people - people aged 65 andover, pregnant women and people with long-term health conditions, including diabetes, kidney disease and chronic obstructive pulmonary disease, are particularly at risk during winter weather.

This year, Aussie flu, the H3N2 strain of the flu virus, has been causing havoc in Britain, causing a number of deaths and hundreds of hospitalisations.

Symptoms are similar to those caused by normal flu but more severe, and include a sudden fever, aching body and loss of appetite.

The NHS says the best way to prevent getting flu is to have the flu jab or flu nasal spray for children aged two to 17.

The health body says: “The flu vaccine gives good protection against flu and lasts for one year.

“If you are over 65 or have a long term health condition, you are also eligible for the pneumococcal vaccine, which provides protection against pneumonia.”

Its top tip is to find out if you’re at risk of getting flu by asking your GP.

If you’re in a high-risk group, you should see your GP to get the vaccination.

The extreme winter weather, nicknamed ‘Beast from the East’, could also trigger symptoms of potentially dangerous condition hypothermia.

Rheumatoid arthritis is one of the most common types of arthritis, and symptoms include inflammation in and around the joints, warm, red skin over the affected joint, and weakness and muscle wasting.

While there is no cure, there are ways proven to ease pain and other symptoms in the form of supplements.

Scientific evidence has been carried out to suggest borage seed oil can be used to treat rheumatoid arthritis.

Borage seed oil, also known as starflower oil, is made from the seeds of the borage plant, a herb native to the Mediterranean region but grown in other countries, including the UK.

But how does it help improve the symptoms of rheumatoid arthritis?

According to Arthritis Research, borage seed oil contains very high levels of two types of polyunsaturated omega-6 essential fatty acids, 20 to 26 per centgamma-linolenic acid (GLA) and linolenic acid (LA, which your body converts to GLA).

The charity explains: “GLA is an essential fatty acid that’s important for maintaining a joint’s cell structure and function. Your body converts it into hormone-like substances called prostaglandins, which regulate your immune system and fight joint inflammation.

“GLA might also suppress inflammatory responses by directly acting on some inflammatory cells.”

Borage seed oil, or starflower oil, is available to buy over the counter from pharmacies and health food shops in the from of capsules or bottled oil.

Starflower oil is available from Holland & Barrett - 50 capsules are £13.99.

Supplementation with the co-enzyme Ubiquinone Q10 can “significantly improve” blood sugar control in Type 2 diabetics, as well as helping sufferers who take statins or have non-alcoholic fatty liver disease (NAFLD), according to an article in The British Journal of Diabetes.

The study comes in the wake of figures showing diabetes as the fastest growing health crisis in the UK with the number of sufferers doubling to 3.7 million in the last 20 years with a further 12.3 million at increased risk of developing Type 2 diabetes.

The co-enzyme Ubiquinone Q10 is a vitamin-like substance which plays a vital role in the body’s energy supply mechanism, acting alongside enzymes converting fats and sugars into energy.

Heart and skeletal muscles have the highest energy requirements of all tissues and are particularly reliant on adequate supplies of Q10 as a result.

Ubiquinone Q10 is also an antioxidant, protecting cells from the potentially damaging effects of toxic free radicals, but production of Ubiquinone Q10 in the body declines with age and Type 2 diabetics are often found to have lower levels of the substance.

The British Journal of Diabetes piece on Ubiquinone Q10 and diabetes pointed to a number of different clinical studies which showed how Type 2 diabetes sufferers who took Ubiquinone Q10 supplements of between 100mg and 200mg a day over a two to three-month period saw their conditions improve.

Dr David Mantle, author of the study in The British Journal of Diabetes, said: “The body of evidence pointing to the potentially beneficial effects of Ubiquinone Q10 supplements for Type 2 diabetes sufferers is substantial.

“As the article outlines, controlled clinical trials have shown significant benefits in blood sugar control and vascular function for Type 2 diabetics who have taken Ubiquinone Q10 on a regular basis.

“Ubiquinone Q10 is also generally well tolerated with no serious adverse effects reported in long-term use and its safety has also been documented in over 200 randomised controlled trials in a wide range of disorders.

The study followed 826 participants in a clinical trial for six-and-a-half years after they were treated with surgery and chemotherapy.

Those who regularly consumed at least two one-ounce servings of nuts each week showed a 42 per cent improvement in disease-free survival and a 57 per cent improvement in overall survival.

Senior author Professor Charles Fuchs, director of Yale Cancer Centre in the US, said: “Further analysis revealed that disease-free survival increased by 46 per cent among the sub-group of nut consumers who ate tree nuts rather than peanuts.”

Healthy Lead author Dr Temidayo Fadelu, a postdoctoral fellow at Dana-Farber Cancer Institute in the US, said: “These findings are in keeping with several other observational studies that indicate that a slew of healthy behaviours, including increased physical activity, keeping a healthy weight, and lower intake of sugar and sweetened beverages – improve colon cancer outcomes.

The researchers said the study also highlighted connections between biological mechanisms that worsen disease – not just in colon cancer, but in certain chronic illnesses such as Type 2 diabetes.

Many previous studies have reported that nuts, among other health benefits, may help to reduce insulin resistance, a condition in which the body has difficulty processing the hormone.

Insulin resistance leads to unhealthy levels of sugar in the blood and is often a predecessor to Type 2 diabetes and related illnesses.

Earlier research among patients with colon cancer has revealed worse outcomes among those with lifestyle factors that heighten insulin resistance, such as obesity, lack of exercise, and a diet with high levels of carbohydrates that quickly raise levels of blood sugar.

Prof Fuchs said: “These studies support the hypothesis that behaviours that make you less insulin resistant – including eating nuts – seem to improve outcomes in colon cancer.

“However, we don’t know yet what exactly about nuts is beneficial.”

He said nuts also might play a positive role by satisfying hunger with less intake of carbohydrates or other foods associated with poor outcomes.

Dr Fuchs acknowledged patients may not be eating nuts owing to concerns about high fat content.

For example, a one-ounce serving of 24 almonds holds about 200 calories, including half a ounce of fat.

But he said: “People ask me if increasing nut consumption will lead to obesity. But what’s really interesting is that in our studies, and across scientific literature in general, regular consumers of nuts tend to be leaner.”

The study findings were published in the Journal of Clinical Oncology.